docs: def parse(self, limit=None):
          """
          We process each of the postgres tables in turn.
          The order of processing is important here, as we build
          up a hashmap of internal vs external identifers
          (unique keys by type to MGI id).  These include allele, marker (gene),
          publication, strain, genotype, annotation (association),
          and descriptive notes.
          :param limit: Only parse this many lines of each table
          :return:
  
          """
          if limit is not None:
              LOG.info("Only parsing first %d rows of each file", limit)
          LOG.info("Parsing files...")
  
          if self.test_only:
              self.test_mode = True
  
          # the following will provide us the hash-lookups
          # These must be processed in a specific order
          self._process_prb_strain_acc_view(limit)
          self._process_mrk_acc_view()
          self._process_all_summary_view(limit)
          self._process_bib_acc_view(limit)
          self._process_gxd_genotype_summary_view(limit)
  
          # The following will use the hash populated above
          # to lookup the ids when filling in the graph
          self._process_prb_strain_view(limit)
          # self._process_prb_strain_genotype_view(limit)
          self._process_gxd_genotype_view(limit)
          self._process_mrk_marker_view(limit)
          self._process_mrk_acc_view_for_equiv(limit)
          self._process_mrk_summary_view(limit)
          self._process_all_allele_view(limit)
          self._process_all_allele_mutation_view(limit)
          self._process_gxd_allele_pair_view(limit)
          self._process_voc_annot_view(limit)
          self._process_evidence_view(limit)
          self._process_mgi_note_vocevidence_view(limit)
          self._process_mrk_location_cache(limit)
          self.process_mgi_relationship_transgene_genes(limit)
          self.process_mgi_note_allele_view(limit)
  
          LOG.info("Finished parsing.")
  
          LOG.info("Loaded %d nodes", len(self.graph))
          return